Super resolution information reproduction by tracking address information in normal resolution

ABSTRACT

An optical disk includes: a substrate shaped in a disk, and having a recording surface; a plurality of recording tracks formed substantially coaxially on the recording surface; a plurality of information pits, which are reproducible by a super resolution reproduction, recorded on the plurality of recording tracks in a recording operation of the optical disk; and an address pit for address reproduction formed in advance to the recording operation on the recording surface with respect to one set of recording tracks adjacent to each other in a radial direction of the optical disk.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related with an optical disk, an optical diskreproducing apparatus, and an optical disk recording apparatus, and morespecifically, it is related with the optical disk and the optical diskreproducing apparatus, in which a high density record is possible.

2. Description of the Related Art

FIG. 1 shows a constitution of an information recording surface of amagneto-optical disk.

In the magneto-optical disk, grooves G, which are approximatelycoaxially arranged guiding grooves, are formed, and lands L are formedalong with the grooves G. Information pits (record marks) are normallyformed on the lands L. In order to read out the information pit withouterror, the groove G is kept in such a state that nothing is recordedthereon.

If the information pit is formed on both of the land L and the groove Gwith respect to the magneto-optical disk, a crosstalk is generated sothat there arises a problem that the information pit cannot be correctlyread.

In order to solve the above-mentioned problem, there is a superresolution reproduction, such as a MSR (Magnetically induced SuperResolution).

The super resolution is such a technology, which is developed in thefield of a microscope, that a high resolution exceeding a usualdefinition is obtained by a special process applied to the imageformation system, or by the post process applied to the image. Forexample, there is one method of dividing a spacial frequency domain intosome pieces, performing the image formation in each domain, andsynthesizing them on the image formation plane. There is another methodof performing an image formation after modulating the object image byuse of a lattice, and demodulating it on the image formation plane.

Hereinbelow, the MSR as one technique of the super resolutionreproduction, will be explained. In the technical field of themicroscope, it is known that the image resolution can be improved bypreparing an optical mask like a pinhole at an objective position. Inthe MSR, a physical mask is not prepared at the recording medium surfaceof the magneto-optical disk, but a mask is formed in efficiency in themedium by use of the temperature distribution in the medium. The MSRenlarges the spacial frequency of the reproduction limit in efficiency,whereby to improve the recording density to about 1.5 to 3 times (see indetail “Atsushi Fukomoto, super resolution in a magneto optical diskwith an active mask” in Japanese Applied Magnetic Academy's paper,Vol.15, No.5.1991, etc.). disk.

However, in the above-mentioned MSR, in order to perform the superresolution reproduction, it becomes necessary to magnetically record theinformation pit, or the address pit for address generation.

Therefore, with respect to the optical disk, on which the address pit isrecorded in advance as a phase pit in the same manner as the informationpit of a ROM disk etc., the above-mentioned super resolutionreproduction cannot be applied to the reproduction of the address pit.Thus, the address pit needs to be formed in such a large size thatallows a normal reproduction (normal resolution reproduction). Even ifthe information pits are formed on both of the land L and the groove Gin order to improve the recording density, it is not possible to makethe address pit correspond to both of the land L and the groove G by oneto one, resulting in a problem that a perfect information reproductioncannot be performed.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an opticaldisk and an optical disk reproducing apparatus, which are not influencedby the crosstalk etc., even if there are intermingled the informationpits, which are reproducible by the super resolution reproduction, andthe address pits, which are only reproducing by the normal reproduction,so as to reproduce the record data perfectly.

According to the present invention, the above object can be achieved bya first optical disk including: a substrate shaped in a disk, and havinga recording surface; a plurality of recording tracks formedsubstantially coaxially on the recording surface; a plurality ofinformation pits, which are reproducible by a super resolutionreproduction, recorded on the plurality of recording tracks in arecording operation of the optical disk; and an address pit for addressreproduction formed in advance to the recording operation on therecording surface with respect to one set of recording tracks adjacentto each other in a radial direction of the optical disk.

In the first optical disk, the information pits, which can be reproducedby the super resolution reproduction, are recorded on a plurality ofrecording tracks. One address pit for address reproduction is formedwith respect to one set of the record tracks adjacent to each other inthe radial direction of the optical disk. Consequently, it is possibleto improve the information recording density, and at the same time, itis possible to perform the recording in which the recording density isimproved, even in such a case that the size of the address pit is notsmall but is large as compared with the information pit.

According to the present invention, the above object can be alsoachieved by a second optical disk including: a substrate shaped in adisk, and having a recording surface; a recording track including aplurality of lands and a plurality of grooves, and formed substantiallycoaxially on the recording surface; a plurality of information pits,which are reproducible by a super resolution reproduction, recorded onboth of the land and the groove in a recording operation of the opticaldisk; and an address pit for address reproduction formed in advance tothe recording operation on the recording surface with respect to one setof the land and the groove adjacent to each other in a radial directionof the optical disk.

In the second optical disk, the information pits, which can bereproduced by the super resolution reproduction, are recorded on both ofthe land and the groove. One address pit for address reproduction isformed with respect to one set of the land and the groove adjacent toeach other in the radial direction of the optical disk, whereby toimprove the information recording density, and it becomes possible toperform a recording in which the recording density is improved even insuch a case that the size of the address pit is not small but is ratherlarge.

According to the present invention, the above object can be alsoachieved by an optical disk reproducing apparatus for reproducing theabove mentioned second optical disk of the present invention. Theoptical disk reproducing apparatus is provided with: an optical pickupfor irradiating a read beam onto the optical disk and readinginformation recorded on the optical disk; a first driving device forsearching the address pit corresponding to a desired land or groove andfor driving the read beam to a recording position of the address pitwhen reproducing the information pit on the desired land or groove; anda second driving device for driving the read beam to the desired land orgroove from the recording position of the address pit.

In the optical disk reproducing apparatus of the present invention, whenthe first driving device reproduces the information on the desired landor groove, the first driving device searches the address pitcorresponding to the desired land or groove, and drives the read beam tothis address pit recording position. After that, the second drivingdevice drives the read beam from the recording position of this addresspit to the desired land or groove. Therefore, just by recording oneaddress pit with respect to one set of the land and the groove, theinformation of the desired land or the desired groove can be reproduced.

The nature, utility, and further features of this invention will be moreclearly apparent from the following detailed description with respect topreferred embodiments of the invention when read in conjunction with theaccompanying drawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, is a diagram for explaining a constitution of an optical disk inthe related art;

FIG. 2, which consist of FIGS. 2A to 2D, are diagrams for explaining aconstitution of an optical disk of a first embodiment;

FIG. 3 is a block diagram which indicates an outline constitution of amagneto-optical disk reproducing apparatus of the first embodiment;

FIG. 4 is a flow chart in the operation of the first embodiment;

FIG. 5 is a diagram showing a tracking error signal in the firstembodiment;

FIG. 6, which consist of FIGS. 6A to 6C, are diagrams for explaining aconstitution of an optical disk of a second embodiment;

FIG. 7, which consist of FIGS. 7A to 7D, are diagrams for explaining aconstitution of an optical disk of a third embodiment; and

FIG. 8 is a flow chart in the operation of the third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings, embodiments of the presentinvention will be now explained.

First Embodiment

FIG. 2 shows a constitution of an optical disk of the first embodiment.

As shown in FIG. 2A, a plurality of lands L and a plurality of groovesG, are prepared on a recording surface of a substrate of amagneto-optical disk. As shown in FIG. 2B, the A-A′ cross section of themagneto-optical disk is made in a concavo-convex state on the substrate100.

A prepit PP (i.e. a phase pit, which is indicated by a slashed circlemark in FIG. 2A) for address generation, is formed on the axis of thegroove G of the magneto-optical disk. In the present embodiment, an areaPA (i.e. prepit area) where the prepits PP are formed, consists of amirror finished surface as shown in FIG. 2C (the B-B′ cross section).

The length of the prepit PP in the direction of the normal line, isgenerally formed longer than an information pit 101 (which is indicatedby a circle mark in FIG. 2A) on the substrate 100. The width of theprepit PP in the radial direction, is almost equal to or larger than thewidth of the groove G as shown in FIGS. 2A and 2D.

Here, the information pit 101 is reproducible by a super resolutionreproduction such as the aforementioned MSR. For example, theinformation pit 101 may be constructed to be detected by the FAD (FrontAperture Detection) of the MSR, in which the high temperature zone inthe information pit heated by the read beam becomes the mask of theinformation pit while the not-heated front portion of the read beambecomes the aperture. Alternatively, the information pit 101 may beconstructed to be detected by the RAD (Rear Aperture Detection) of theMSR, in which the high temperature zone in the information pit heated bythe read beam becomes the aperture while the not-heated rear portion ofthe read beam becomes the mask. Further, the information pit 101 may beconstructed to be detected by another super resolution reproductiontechnique, in which the reproduction film composing the information pitis magnetized inwardly by heating the film by the read beam, to enablethe super resolution. Various known super resolution reproductiontechniques can be employed to the information pit 101 of the present.

FIG. 3 is a block diagram indicating an outline constitution of amagneto-optical disk recording and reproducing apparatus.

In FIG. 3, the magneto-optical disk recording and reproducing apparatusis provided with a spindle motor 1, a magnetic head 2a, and an opticalpickup 2b. The spindle motor 1 rotationally drives a magneto-opticaldisk DK. The optical pickup 2b is interlocked with the magnetic head 2a,and is moved in the radial direction of the magneto-optical disk DK byan actuator. The optical pickup 2b includes a laser light source, alens, a photodetector, and so on.

The magneto-optical disk recording and reproducing apparatus is adaptedto irradiate a laser light spot to the magneto-optical disk DK at thetime of recording and reproducing the data, and detect the strength ofthe reflected light at the time of reproducing the data. The reflectedlight is generated such that the polarization plane thereof is slightlyrotated on the magneto-optical disk DK, to which the light spot isirradiated, by the magnetic Kerr effect. The magneto-optical diskrecording and reproducing apparatus is also adapted to output RF (RadioFrequency) signal, which is obtained by photo-electrically convertingthe strength of the reflected light.

The magneto-optical disk recording and reproducing apparatus is providedwith a spindle-servo circuit 3, a focus-servo circuit 4, atracking-servo circuit 5, a head-servo circuit 6, a head amplifier 7, anRF amplifier 8, an EFM decoder 9, a system controller 10, an operationunit 11, and a display section 12.

The spindle-servo circuit 3 controls the spindle motor 1. Thefocus-servo circuit 4 controls the focus of the optical spot irradiatedto the magneto-optical disk DK from the optical pickup 2b. Thetracking-servo circuit 5 controls the movements of the track positionsof the magnetic-head 2a and the optical pickup 2b. The head-servocircuit 6 controls the magnetic head 2a. The head amplifier 7 amplifiesthe output signal of the optical pickup 2b. The RF amplifier 8 generatesa reproduction signal from the output of the head amplifier 7, andgenerates various control signals. The EFM decoder 9 restores the EFMsignal, which is outputted from the RF amplifier 8 at the time of datareproduction, and outputs digital output data. The system controller 10controls the whole apparatus at the time of data reproduction. Operationinputs for data reproduction, are inputted through the operation unit11. The operation unit 11 includes operation switches, such as areproduction switch (“PLAY” switch). The display section 12 performsvarious displays at the time of data reproduction.

Nextly, the operation of the present embodiment will be explained withreference to the flow chart of FIG. 4.

In the following explanation, it is assumed that, whether the positionto reproduce/record the information pit is on the land L or the grooveG, is indicated by a least significant bit (LSB) of the address data.More concretely, it is assumed that the basic address data, forspecifying one set of the land and the groove, including the land Lwhich information pit is to be reproduced or recorded, is equal to“0100”, and that the bit information indicating the land L is X (X:0 or1). At this time, the address data becomes equal to “0100 X”. In thiscase, the basic address data of the target, is recorded on the groove G.At the inner and outer circumferential sides of the groove G, thereexists the land L. Thus, it becomes necessary to determine in advancewhether the land corresponding to the basic address data is the innercircumferential side or the outer circumferential side. When the grooveindicated by the basic address data is detected, it becomes possible toimmediately perform jumping to a right land, by monitoring whether thetracking error signal is deflected to the plus (+) side or the minus (−)side, as shown in FIG. 5.

In FIG. 4, firstly, the system controller 10 controls the tracking-servocircuit 5 to set up so as to trace the groove (step S1).

Next, the system controller 10 reads the present address data (basicaddress data) obtained through the pickup 2b, the head amplifier 7, theRF amplifier 8, and the EFM decoder 13 by irradiating the light spot tothe prepit (step S2). And, the system controller 10 compares thusobtained data with the portion of the target address data except theleast significant bit thereof, and seeks to the target track (i.e. toone set of the land and the groove) (step S3).

When it reaches to the target track, the system controller 10 judges theleast significant bit (=X) of the address data, and judges whether thefinal target address data corresponds to the groove or not (step S4).

If the final target address corresponds to the groove G, it is concludedthat the seeking operation is already completed, so that the seekingprocess is ended, since in the present embodiment, the basic addressdata is recorded on the groove G.

Moreover, if the final target address corresponds to the land, thesystem controller 10 controls the tracking-servo circuit 5 to switch thetracking servo-control so as to trace the land L and draw it into theland L, and ends the seeking process (step S5).

After that, the super resolution reproduction operation of theinformation pits, which are recorded on the groove G or the land L, isperformed under the control of the system controller 10.

As described above, even in the case that there are intermingled theinformation pits, which are reproducible by the super resolutionreproduction, and the address pits, which are only reproducible by thenormal reproduction, the reproduction is not influenced by the crosstalketc., the record data can be perfectly reproduced, and the recordingdensity of the magneto-optical disk can be also improved, according tothe present embodiment.

Second Embodiment

FIG. 6 shows an optical disk of the second embodiment. In this secondembodiment, the prepits are prepared in the land.

As shown in FIG. 6A, a plurality of lands L and a plurality of grooves Gare prepared on a recording surface of a substrate of themagneto-optical disk. As shown in FIG. 6 B, the D-D′ cross section ismade in the concavo-convex state on a substrate 100.

The prepits PP (i.e. the phase pits) for address generation are formedon the axis of each land L of the magneto-optical disk. In the presentembodiment, the groove G is also formed on this area PA (i.e. prepitarea), in which the prepits PP are formed, in parallel to the land asshown in FIG. 6A.

The length of the prepit PP in the direction of the normal line, isformed generally longer than the information pit 101 (which is indicatedby a circle mark in FIG. 6A) as shown in FIG. 6A. The width of theprepit PP in the radial direction is almost equal to or less than thewidth of the land L, as shown in FIGS. 6A and 6C.

The searching operation for the target address in this secondembodiment, is similar to that of the first embodiment, and it issufficiently explained just by interchanging the land L and groove G inthe explanation of the first embodiment.

Even in the case that there are intermingled the information pits, whichare reproducible by the super resolution reproduction, and the addresspits, which are only reproducible by the normal reproduction, thereproduction is not influenced by the crosstalk etc., the record datacan be perfectly reproducible, and the recording density of themagneto-optical disk can be also improved according to the secondembodiment, as in the case of the first embodiment.

Third Embodiment

FIG. 7 shows a constitution of the optical disk of the third embodiment.The prepits PP are formed in the third embodiment such that the centralaxis of each prepit PP is located between the central axis of the grooveand the central axis of the land.

As shown in FIG. 7A, a plurality of lands L and a plurality of grooves Gare prepared on a recording surface of a substrate of themagneto-optical disk. As shown in FIG. 7B, the F-F′ cross section ismade in the concavo-convex state on a substrate 100 of the optical disk.

The prepits (which are indicated by a slash circle mark in FIG. 7A) areformed such that the axis of the prepit PP (i.e. the phase pit) foraddress generation, is located between the axis of the groove G and theaxis of the land L of the magneto-optical disk. In the presentembodiment, the area PA (i.e. the prepit area) in which the prepits areformed, consists of the mirror finished surface as shown in FIG. 7C (theH-H′ cross section).

The length of the prepit pit in the direction of the normal line isgenerally formed longer than the information pit 101 (which is indicatedby a circle mark in FIG. 7A). The width of the prepit in the radialdirection is almost equal to or less than the sum of the width of thegroove G and the width of the land L as shown in FIGS. 7A and 7D.

Nextly, the operation of the present embodiment will be explained withreference to the flow chart of FIG. 8.

In the following explanation, in the similar manner as the firstembodiment, it is assumed that whether the position to reproduce/recordthe information pit is on the land L or on the groove G is indicated bythe least significant bit of the address data, and that the target basicaddress data is recorded as a prepit between the axis of the groove Gand the axis of the land L. Since the groove G or the land L exists inthe inner circumferential side and the outer circumferential side ofthis prepit, the target groove G or land L is uniquely determined. Thus,it is not necessary to determine beforehand jumping to the innercircumferential side or jumping to the outer circumferential sideaccording to the basic address data, as in the first embodiment. Bymonitoring whether the tracking error signal is deflected to the plus(+) side or to the minus (−) side, it becomes possible to performjumping immediately to the right land or groove.

In FIG. 8, firstly, the system controller 10 controls the tracking-servocircuit 5 to set up so as to trace the groove G or the land L (stepS10). In this third embodiment, this set-up can be performed whether itis the groove G or the land L.

Nextly, the system controller 10 controls the tracking-servo circuit 5to give, to the pickup 2b, the offset voltage having such a voltage tomove the read beam to a position between the axis of the groove G andthe axis of the land L (step S11). As the result, the read beam is movedto be at the position between the axis of the groove G and the axis ofthe land L, so that it becomes possible to read out the signalcorresponding to the prepit.

Nextly, the system controller 10 reads the present address data (i.e.the basic address data) obtained through the pickup 2b, the headamplifier 7, the RF amplifier 8, and the EFM decoder 13, by irradiatingthe light spot onto the prepit (step S12). And, the system controller 10compares thus obtained data with the portion of the target address dataexcept the least significant bit thereof. The system controller 10controls the tracking-servo circuit 5 again to set up so as to trace thegroove G or the land L (step S13). Then, seeking to the vicinity of thetarget track (i.e. one set of the land and groove) is performed (stepS14).

Nextly, the system controller 10 controls the tracking-servo circuit 5again to give, to the pickup 2b, the offset voltage having such avoltage to move the read beam to the position between the axis of thegroove G and the axis of the land L (step S15). Thus, the read beam ismoved to be at the position between the axis of the groove G and theaxis of the land L, so that the signal corresponding to the prepit canbe read out. Then, the system controller 10 reads the present addressdata (i.e. the basic address data) obtained through the pickup 2b, thehead amplifier 7, the RF amplifier 8, and the EFM decoder 13 (step S16).The system controller 10 compares thus obtained data with the portion ofthe target address data except the least significant bit thereof, andjudges whether it has reached to the target track or not (step S17).

If it reaches the target track (YES), the system controller 10 judgesthe least significant bit (=X) of the address data, judges whether thefinal target address data corresponds to the groove or not, and performsjumping to the groove G or the land L according to the least significantbit of the address (step S18).

After that, the super resolution reproducing operation of theinformation pit recorded on the groove G or the land L is performedunder the control of the system controller 10.

On the other hand, if it does not reach the target track at the step S17(NO), the processes of the steps S13 to S17 are repeated until itreaches the target track (YES).

As described above in detail, even in the case that there areintermingled the information pits, which are reproducible by the superresolution reproduction, and the address pits, which are onlyreproducible by the normal reproduction, the reproduction is notinfluenced by the crosstalk etc., the record data can be perfectlyreproduced, and the recording density of the magneto-optical disk can beimproved, according to the third embodiment, as in the first and secondembodiments.

Moreover, the land L and the group G are formed on the optical disk inthe above embodiments. However, the present invention can be adapted tothe optical disk on which the land L and the group G are not formed.

As described above in detail, according to one aspect of the presentinvention, since the information pits, reproducible by the superresolution reproduction, are recorded on a plurality of the recordtracks, and since one address pit for address reproduction is formedwith respect to one set of the recording tracks adjacent to each otherin the radial direction of the optical disk, the information recordingdensity can be improved. Further, even in the case that the size of theaddress pit is not small but is large as compared with the informationpit, the recording operation in which the recording density is improved,becomes possible.

According to another aspect of the present invention, since one addresspit for address reproduction is formed with respect to one set of theland and the groove adjacent to each other in the radial direction ofthe optical disk, the information recording density can be improved.Further, even in the case that the size of the address pit is not smallbut is large, the recording operation in which the recording density isimproved, becomes possible.

According to another aspect of the present invention, since only oneaddress pit is recorded with respect to one set of the land and thegroove, the information pit on the desired land or the desired groovecan be reproduced. Further, even in the case that the size of theaddress pit is not be small, the reproduction of the optical disk inwhich the recording density is improved, becomes possible.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

1. An optical disk, to be reproduced by forming a light spot with apredetermined diameter thereon, comprising: a substrate shaped in amagneto-optical disk, and having a recording surface; a plurality ofrecording tracks formed substantially coaxially on the recordingsurface; a plurality of information pits, which are recorded on saidplurality of recording tracks as magnetization directions at saidrecording surface in a magneto-optical recording operation and arearranged with such a high pit density as to be non-reproducible by anormal resolution reproduction by use of the light spot but reproducibleby a super resolution reproduction by use of the light spot; and anaddress pit for address reproduction formed in advance to the recordingoperation on the recording surface with respect to one set of recordingtracks adjacent to each other in a radial direction of the optical disk,having a convex or concave shape on the recording surface and beingarranged with such a low pit density as to be reproducible by a normalresolution reproduction by use of the light spot.
 2. An optical disk asset forth in claim 1, wherein said address pit is larger than saidinformation pit in the radial direction of said optical disc.
 3. Anoptical disk, to be reproduced by forming a light spot with apredetermined diameter thereon, comprising: a substrate shaped in amagneto-optical disk, and having a recording surface; a recording trackincluding a plurality of lands and a plurality of grooves, and formedsubstantially coaxially on the recording surface; a plurality ofinformation pits, which are recorded on both of the land and the grooveas magnetization directions at said recording surface in amagneto-optical recording operation and are arranged with such a highpit density as to be non-reproducible by a normal resolutionreproduction by use of the light spot but reproducible by a superresolution reproduction by use of the light spot; and an address pit foraddress reproduction formed in advance to the recording operation on therecording surface with respect to one set of the land and the grooveadjacent to each other in a radial direction of the optical disk, havinga convex or concave shape on the recording surface and being arrangedwith such a low pit density as to be reproducible by a normal resolutionreproduction by use of the light spot.
 4. An optical disk as set forthin claim 3, wherein said address pit is formed on said groove.
 5. Anoptical disk as set forth in claim 3, wherein said address pit is formedon said land.
 6. An optical disk as set forth in claim 3, wherein saidaddress pit is formed such that the central axis of said address pit ispositioned between the central axis of the groove and the central axisof the land.
 7. An optical disk as set forth in claim 3, wherein saidaddress pit is larger than said information pit in the radial directionof said optical disc.
 8. An optical disk reproducing apparatus forreproducing an optical disk, to be reproduced by forming a light spotwith a predetermined diameter thereon, comprising: a substrate shaped ina magneto-optical disk, and having a recording surface; a recordingtrack including a plurality of lands and a plurality of grooves, andformed substantially coaxially on the recording surface; a plurality ofinformation pits, which are recorded on both of the land and the grooveas magnetization directions at said recording surface in amagneto-optical recording operation and are arranged with such a highpit density as to be non-reproducible by a normal resolutionreproduction by use of the light spot but reproducible by a superresolution reproduction by use of the light spot; and an address pit foraddress reproduction formed in advance to the recording operation on therecording surface with respect to one set of the land and the grooveadjacent to each other in a radial direction of the optical disk, havinga convex or concave shape on the recording surface and being arrangedwith such a low pit density as to be reproducible by a normal resolutionreproduction by use of the light spot, said apparatus comprising: anoptical pickup for irradiating a read beam onto said optical disk toform the light spot with the predetermined diameter and readinginformation recorded on said optical disk; a first driving means forsearching the address pit corresponding to a desired land or groove bydriving the optical pickup, and for driving the read beam to a recordingposition of the address pit when reproducing the information pit on thedesired land or groove; and a second driving means for driving the readbeam to the desired land or groove from the recording position of theaddress pit.
 9. An optical disk reproducing apparatus as set forth inclaim 8, wherein said address pit is formed on said groove.
 10. Anoptical disk reproducing apparatus as set forth in claim 8, wherein saidaddress pit is formed on said land.
 11. An optical disk reproducingapparatus for reproducing an optical disk, to be reproduced by forming alight spot with a predetermined diameter thereon, comprising: asubstrate shaped in an optical disk, and having a recording surface; arecording track including a plurality of lands and a plurality ofgrooves, and formed substantially coaxially on the recording surface; aplurality of information pits, which are recorded on both of the landand the groove at said recording surface in an optical recordingoperation and are arranged with a first pit density; and an address pitfor address reproduction formed in advance to the recording operation onthe recording surface with respect to one set of the land and the grooveadjacent to each other in a radial direction of the optical disk, havinga convex or concave shape on the recording surface and being arrangedwith a second pit density, which is lower than said first pit density,said apparatus comprising: an optical pickup for irradiating a read beamonto said optical disk to form the light spot with the predetermineddiameter and reading information recorded on said optical disk; a firstdriving means for searching the address pit corresponding to a desiredland or groove by driving the optical pickup, and for driving the readbeam to a recording position of the address pit when reproducing theinformation pit on the desired land or groove; and a second drivingmeans for driving the read beam to the desired land or groove from therecording position of the address pit.
 12. An optical disk reproducingapparatus as set forth in claim 11, wherein a plurality of address pitseach having a same construction as said address pit are formed on therecording surface such that one address pit corresponds, on one line inthe radial direction of said optical disk, to said one set of the landand the groove.
 13. An optical disk reproducing apparatus as set forthin claim 11, wherein said address pit is formed on said groove.
 14. Anoptical disk reproducing apparatus as set forth in claim 11, whereinsaid address pit is formed on said land.